Inner or outer engine combustor liners are typically substantially circularly radially symmetrical. Furthermore, such combustor liners or parts for aircraft engines or gas turbines typically require a plurality of holes, often thousands, having a small diameter and being precisely placed to satisfy stringent fluid flow requirements desirable for satisfactory engine operation. One problem associated with the fluid flow requirements for such engine combustor parts is the capability to measure fluid flow in the relevant dynamic range of flows, given a predetermined pressure differential. More particularly, measuring the effect on the fluid flow of a misplaced or poorly formed hole in the part generally exceeds the capabilities of present fluid flow sensor technology, such as on the order of 0.030 lbs.mass/second for a row of holes or about 75 cubic feet per minute. Yet another problem is satisfactorily testing the part in a manner that addresses the large fluid or air flows associated with the operation of such an engine liner or part. Thus, large and costly flow test installations are frequently necessary for "full" flow testing of the combustor parts.
One approach to solving these problems has included performing random "spot checks" of hole diameters using gauge pins to assist in making adjustments to the drilling, usually performed by a laser beam, to fabricate or form the holes. A full flow test may then be performed on the finished part at a "flow" test installation or laboratory, as described above; however, this approach has several disadvantages. First, hole diameter checking using gauge pins is notoriously inexact, and furthermore may not provide a true indication of fluid flow. Likewise, such a technique fails to take into account hole taper, hole angle of orientation with respect to the part wall, or other possible hole fabrication anomalies other than hole size that may also affect flow. Furthermore, once the part is capable of being "fully" flow tested, modifications or corrections to the part are not feasible and the part must ultimately be scrapped if it does not perform within desired specifications. A need thus exists for an alternative method or apparatus to measure the fluid flow through holes in an engine combustor part or liner that satisfactorily overcomes these problems.